linux-kernel - Re: [PATCH, resend] x86/PCI: don't export a _

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Date:	Thu, 17 Feb 2011 22:12:18 -0200
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Jan Beulich <JBeulich@...ell.com>, mingo@...e.hu,
	tglx@...utronix.de, hpa@...or.com, arozansk@...hat.com,
	Michal Marek <mmarek@...e.cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH, resend] x86/PCI: don't export a __devinit function

Em 17-02-2011 21:12, Yinghai Lu escreveu:
> On Thu, Feb 17, 2011 at 10:12 AM, Mauro Carvalho Chehab
> <mchehab@...hat.com> wrote:
>> Em 17-02-2011 14:08, Jan Beulich escreveu:
>>> Exporting a __devinit function (pcibios_scan_specific_bus()) isn't
>>> correct. (Michal, any reason why modpost only warns about exported
>>> __init functions?) Short of being able to think of a better solution,
>>> and short of making the whole call tree (reaching into the arch-
>>> independent part of the PCI subsystem) non-__devinit, export the
>>> symbol only when HOTPLUG is enabled (which is always the case for non-
>>> expert configurations), use section mismatch avoidance annotations for
>>> that case (knowing that __devinit functions will not be discarded),
>>> and mark the symbol __devinit only in the !HOTPLUG case.
>>>
>>> Consequently, EDAC_I7CORE (consuming the export) then has to depend on
>>> HOTPLUG.
>>
>> Having the entire i7core_edac driver depending on HOTPLUG, just because
>> a few BIOSes want to hide the non-core PCI devices doesn't seem nice.
>> One alternative would be to enclose the code that needs this function
>> with #ifdef CONFIG_HOTPLUG.
>>
>>> A fundamental question of course if whether this driver has
>>> to use that function in the first place (i.e. whether it wouldn't be
>>> better to just remove the export) - the problem it tries to address
>>> happens on other systems too, but the PCI bus the devices in question
>>> live on isn't necessarily bus 255. For the affected system I have, the
>>> alternative approach is to set pcibios_last_bus from __pci_mmcfg_init()
>>> based on the highest bus number on segment 0 being covered by MCFG.
>>
>> I received a few days ago a report that some BIOSes that hide those
>> PCI devices also use a different address for the last bus (0x3f, instead
>> of 0xff). So, it seems that the better would be to use an alternative
>> way to retrieve the last bus.
> 
> just append "pci=lastbus=255" will get all those devices.

I know, but the better would be if this could be detected, instead of
relying on a modprobe parameter.

Cheers,
Mauro
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